UNIVERSITY   OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL   EXPERIMENT  STATION 

CIRCULAR  No.  244 
June,  1922 

CENTRAL  WIRE  BRACING  FOR  FRUIT  TREES 

By  L.  C.  BARNARD 


During  the  past  few  years  the  Agricultural  Experiment  Station 
has  tested  the  use  of  wire  braces  as  a  substitute  for  wooden  props  to 
support  the  limbs  of  fruit  trees.  The  efficiency  of  wire  braces  and 
the  methods  of  applying  them  have  been  studied  in  the  Experiment 


IKS  ^^1 

BiSHfiKv 

m  '  &£    m^PH 

Bracing   fruit    trees    by   means    of   wiring,    Experimental    Orchard,    University 
Farm,  Davis,  California.      (Frontispiece.) 


Z  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Station  orchards  and  also  in  a  number  of  commercial  orchards,  in 
cooperation  with  leading  fruit  growers.  Wire  braces  have  proved  so 
satisfactory  that  they  have  aroused  widespread  inquiry. 

THE    WIRE    BRACE 

As  shown  in  figures  1  and  7  the  tree  is  braced  from  within  by 
means  of  wires.  Each  limb  is  supported  by  a  wire,  one  end  of  which 
is  attached  to  the  inner  side  of  the  limb  by  means  of  a  screw  eye  or 
staple.  The  other  ends  of  the  wires  come  together  in  the  center  of 
the  tree  where  they  are  attached  to  a  single  ring  at  the  proper  height 
(see  fig.  1). 


Fig.  1. — Looking  down  on  system  of  wire  bracing  in  a  prune  tree.    Note  taut- 
ness  and  number  of  wires  used,  representing  wooden  props. 


METHOD    OF   BRACING 

In  preparing  to  brace  trees  in  this  way  approximately  150  to  200 
feet  of  the  wire  should  first  be  uncoiled  along  the  row  of  trees  to  be 
wired,  so  as  to  be  drawn  toward  the  worker  as  he  goes  from  tree  to 
tree.  A  small  branch  or  weight  should  be  attached  to  the  farther  end 
to  prevent  recoiling  and  kinking.  On  the  other  end  is  made  a  tem- 
porary hook  which  is  fastened  to  any  convenient  twig  in  reach  of  the 
worker  when  on  the  ladder.     About  a  dozen  washers  or  rings  may  be 


Fig.  2. — Showing  wires  fastened  to  ring  in  a  very  slipshod  manner.  Compare 
this  tie  with  the  one  in  figure  3  for  neatness,  economical  use  of  wire,  and  possibili- 
ties for  pulling  out  under  a  strain. 


Fig.  3. — Showing  japanned  harness  ring,  also  six  figure  eight  ties,  same  as 
used  on  hay  balers.  Note  neatness  of  tie,  also  economical  use  of  wire.  Will  not 
pull  out. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

carried  on  a  wire  hook  attached  to  the  belt.  Pliers,  staples,  screw 
eyes,  hammer,  and  awl  should  be  accessible  for  rapid  work.  The 
operator  is  now  ready  to  ascend  the  ladder  which  is  set  in  the  center 
of  the  tree  as  shown  in  the  frontispiece. 

A  screw  eye  or  staple  is  inserted  on  the  inner  side  of  each  of  the 
four  or  five  main  limbs.  The  smaller  branches  may  in  turn  be  wired 
to  the  main  limbs. 

The  staple  or  screw  eye  should  be  inserted  at  the  proper  height. 
If  placed  too  low  on  the  limb  the  latter  may  break  above  the  support ; 
if  placed  too  far  out  on  the  limb  there  is  a  tendency  to  pull  the  ends 
of  the  branches  in,  giving  the  tree  a  bowed  appearance. 

An  awl  may  be  used  to  puncture  the  limb  for  insertion  of  the 
screw  eye.  The  screw  eye  should  be  screwed  down  until  its  lower  side 
just  touches  the  bark  and  is  left  parallel  to  the  limb  rather  than  cross- 
wise ;  if  left  crosswise  it  might  cause  restriction  of  the  sap  flow.  This 
caution  also  applies  to  the  position  of  staples  when  they  are  used. 

After  the  screw  eyes  are  in  place,  the  hooked  end  of  the  uncoiled 
wire  is  inserted  through  one  of  the  eyes  and  securely  twisted  to  pre- 
vent slipping  or  pulling  out.  The  ordinary  figure  eight  tie,  as  used 
on  hay  balers,  is  recommended  (see  fig.  2).  After  tying,  the  wire  is 
drawn  toward  the  center  and  cut  the  desired  length.  From  a  screw 
eye  on  the  opposite  side  of  the  tree  the  same  operation  of  wiring  is 
repeated.  A  washer,  or  harness  ring,  is  next  secured  to  the  loose  end 
of  a  wire  that  has  been  fastened  to  a  screw  eye.  With  this  washer  or 
ring  in  one  hand  the  loose  end  of  the  second  wire  is  directed  through 
the  washer  or  ring,  pulled  taut,  and  twisted  securely.  The  wires  should 
not  be  pulled  too  tight  nor  left  too  loose;  they  should  simply  take 
up  the  slack  of  the  branches  induced  by  gravity.  The  ring  is  now 
suspended  in  the  center  of  the  tree  by  the  wires  from  opposite  screw 
eyes  and  it  is  easy  to  attach  the  other  wires. 


NUMBER    OF   TREES    WIRED    PER    DAY 

The  number  of  trees  which  may  be  wired  in  a  day  depends  on 
the  size  of  the  tree  and  whether  staples  or  screw  eyes  are  used,  more 
time  being  required  to  insert  the  latter.  About  35  to  40  large  peach 
trees  have  been  wired  by  the  writer  in  nine  hours. 

In  one  orchard  of  French  prune  trees,  twenty  to  thirty  years  old 
and  heavily  loaded,  many  so  large  as  to  require  a  double  tier  of  wires, 
only  20  to  25  trees  could  be  wired  by  two  men,  one  man  working  in 
the  center  of  the  tree  and  the  other  around  the  outside. 


Circular  244] 


CENTRAL  WIRE  BRACING  OF  FRUIT  TREES 


TIME  OF  YEAR  TO  WIRE  TREES 

If  wired  while  the  crop  is  on  the  tree,  the  worker  cannot  see  well ; 
also  there  is  some  loss  of  leaves  and  fruit.  The  fact  that  the  wood 
is  soft,  however,  facilitates  the  work  with  the  screw  eyes  or  staples. 
If  wired  in  the  fall  when  the  leaves  are  off,  after  pruning,  not  only 
can  the  worker  see  better,  but  wires  will  not  be  placed  on  limbs  which 
may  be  pruned  out  later.  At  this  season  the  limbs  are  in  normal 
position,  are  not  weighted  down  with  fruit,  and  do  not  need  propping 
before  securing  the  wire  to  the  ring. 

The  time  of  wiring  may  depend  upon  a  number  of  factors,  like 
grower's  time,  condition  of  the  trees,  urgent  necessity  of  support, 
number  of  props  on  hand  for  the  season,  cost  of  material,  and  labor 
available. 


Fig.  4. — Showing  wire  leading  to  screw  eye  which  has  finally  grown  over  by 
succeeding  layers  of  growth. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


YOUNG   TREES    MAY   REQUIRE    REWIRING    LATER 

Trees  which  are  wired  at  an  age  of  from  four  to  eight  years  may 
later  require  additional  wiring.  In  the  case  of  tall  trees  a  second  tier 
of  wires  is  sometimes  advantageous. 


ADVANTAGES    OF    WIRE     BRACING     SHOWN     BY    COMPARISON 


Wire  Bracing 

1.  Practically  permanent,  lasting 
from  20  to  30  years. 

2.  Cost  of  material  for  wiring  a 
tree  is  comparatively  cheap  and  the 
depreciation  is  very  low. 

3.  Wiring  can  be  done  at  almost 
any  season  of  the  year. 

4.  Wire  bracing  does  not  interfere 
with  tillage  and  is  not  affected  by 
irrigation. 

5.  An  orchard  with  trees  centrally 
wired  does  not  make  an  unattractive 
appearance. 

6.  With  wire  bracing  the  strain  on 
any  one  limb  is  supported  by  all 
limbs,  and  during  wind  storms  the 
braces  are  secure. 

7.  Wire  bracing  does  not  interfere 
with  harvesting. 


Wooden  Props 

1.  Props  usually  last  only  from 
three  to  five  years,  and  must  be  stored 
when  not  in  use. 

2.  The  cost  of  material  for  prop- 
ping is  expensive  and  the  depreciation 
high. 

3.  Wooden  props  must  be  placed 
under  the  limbs  during  the  fruiting 
season. 

4.  Wooden  props  are  a  great  incon- 
venience in  cultivating  and  often  settle 
or  fall  during  irrigation,  allowing 
limbs  to  break. 

5.  An  orchard  with  several  thou- 
sand wooden  props  is  unsightly. 

6.  Each  limb  is  supported  separ- 
ately and  is  allowed  to  whip  in  the 
wind,  props  being  often  dislodged. 

7.  Wooden  props  are  inconvenient 
because  a  fruit  picker  must  continu- 
ally dodge  and  move  his  ladder  around 
them;  they  are  also  in  the  way  of  the 
orchard  truck. 


EQUIPMENT  NECESSARY  AND  COST  OF  MATERIAL 


Ladders  (small  or  large),  hammer,  pliers,  staples  or  screw  eyes 
of  various  sizes,  %"  iron  washers  (inside  diam.),  V/2"  japanned 
malleable  iron  harness  rings,  galvanized  wire  of  various  calibres, 
preferably  No.  14. 


Circular  244] 


CENTRAL  WIRE  BRACING  OF  FRUIT  TREES 


Though  prices  may  vary  several  times  during  any  one  year,  the 
following  quotations,  obtained  in  November,  1921,  may  be  of  value  as 
a  basis  for  estimating  the  cost  of  materials  used  in  wire  bracing. 

Galvanized  wire  No.  14  (approx.  250  lbs.)  $17.67  per  coil 

Screw  eyes,  No.  107,   (large  eye)   .72  per  gross 

Screw  eyes,  No.  209,   (small  eyes)   .72  per  gross 

Screw  eyes,  No.  108    (smaller    caliper)  .75  per  gross 

Harness  rings   (japanned  malleable  iron),  1^" 3.25   per  gross 

Harness  rings  (japanned  malleable  iron),  l1/^" 2.25  per  gross 

Harness  rings  (japanned  malleable  iron),  1" 1.40  per  gross 

Iron  washers   (inside  diam.   %")  .12  per  lb. 

Staples,  %"  to  2" .07  per  lb. 

Galvanized  wire,  No.  14 — 1  coil  or  250  lbs.,  approx.  14,625  ft. 

Iron  washers,  %"  size 12  per  lb. 

Staples,   %"  size 416  per  lb. 

Staples,  1"  108  per  lb. 

Staples,  \V±"  87  per  lb. 

Staples,  iy2"  72  per  lb. 

Staples,  1%"  72  per  lb. 

Staples,  2"  58  per  lb. 


Fig.  5. — A  heavily  loaded  Robe  de  Sargeant  prune  tree  wire  braced. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


COMPARATIVE    COST 

Material. — Assuming  that  a  full-bearing  tree  of  average  size  re- 
quires at  least  eight  props  and  that  the  minimum  life  of  wire  braces 
is  20  years,  and  that  of  the  props  three  years,  the  comparative  cost 
of  propping  and  wiring,  at  current  prices  of  materials,  is  as  follows : 


Wire  Bracing 
No.  14  gal.  wire  =  58'  per  lb. 
8  wires  5'  long  =  40'  @  7c  per  lb.  $.05 

8  screw  eyes  @  72c  per  gross 04 

1  harness  ring  @  $3.25  per  gross     .02 

Cost  per  tree,  20-year  period  $.11 


Wooden  Props 

8  props  1"  X  2"  X  10'  @  $40  per 
thou.  (M)  equals  13:3  @  4c  =  $  .55 
per  tree. 

For  a  20-year  period  the  cost  for 
wooden  braces  would  be  $3.66  per 
tree. 


Fig.  6. — Propped  Robe  de  Sargeant  prune  tree  in  same  block  as  tree  in  fig.  5. 
Note  number  of  wooden  props  used  and  the  amount  of  space  not  accessible  to 
orchard  operations. 


Circular  244]  CENTRAL  WIRE  BRACING  OF  FRUIT   TREES  9 

Labor. — Wooden  props,  for  any  one  year,  can  be  more  quickly 
installed  than  wire  braces;  the  labor  cost  for  a  single  season  would 
therefore  be  less.  Over  a  twenty-year  period,  however,  the  cumulative 
cost  of  wooden  propping  would  greatly  exceed  that  of  wiring,  con- 
sidering that  the  props  must  be  hauled  into  and  out  of  the  orchard 
each  year. 

HELPFUL  HINTS 

1.  For  convenient  work  the  ladder  should  be  set  up  in  the  center 
of  the  tree.     (See  frontispiece.) 

2.  A  tough  leather  glove  worn  on  the  hand  used  in  twisting  the 
wire  is  of  considerable  help. 

3.  It  is  a  less  serious  mistake  to  place  the  wires  too  high  than  too 
low.    If  placed  too  low,  breakage  occurs  above  the  screw  eye  or  staple. 

4.  Staples  can  be  more  quickly  installed  than  screw  eyes.  The 
ordinary  barbed  wire  staples  are  best  for  the  main  limbs.  Small 
chicken  wire  staples  should  not  be  used  for  the  main  limbs,  as  they 
will  pull  out. 

5.  After  starting  the  screw  eye,  time  can  be  saved  by  putting  the 
point  of  the  awl  through  the  eye  and  using  it  as  a  lever  to  twist  the 
screw  eye  into  place. 

6.  When  staples  are  used  they  should  be  driven  in  as  far  as  pos- 
sible, thus  allowing  the  wounds  to  heal  over  sooner. 


10 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


Fig.   7. — Showing  wire  bracing  system  supporting  the  weight   of  the  worker. 
Photograph  of  wired  peach  tree  in  experimental  orchard,  Davis,  California. 


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271. 
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275. 

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282. 

283. 
285. 
286. 
287. 
294. 
297. 
298. 


Report  of  Progress  in  Cereal  Investiga- 
tions. 

Vine  Pruning  in  California,  Part  I. 

Vine  Pruning  in  California,  Part  II. 

Utilization  of  the  Nitrogen  and  Organic 
Matter  in  Septic  and  Imhoff  Tank 
Sludges. 

Irrigation  and  Soil  Conditions  in  the 
Sierra  Nevada  Foothills,  California. 

Melaxuma  of  the  Walnut,  "Juglans  regia." 

Citrus  Diseases  of  Florida  and  Cuba 
Compared  with  Those  of  California. 

Size  Grades  for  Ripe  Olives. 

A  Spotting  of  Citrus  Fruits  Due  to  the 
Action  of  Oil  Liberated  from  the  Rind. 

Experiments  with  Stocks  for  Citrus. 

Growing  and  Grafting  Olive  Seedlings. 

A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California. 

Preliminary  Report  on  Kearney  Vineyard 
Experimental  Drain. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 

The  Pomegranate. 

Grain  Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

The  Milk  Goat  in  California. 

Commercial  Fertilizers. 

Vinegar  from  Waste  Fruits. 

Bean  Culture  in  California. 

The  Almond  in  California. 

Seedless  Raisin  Grapes. 


No. 
299. 
300. 
304. 

308. 


309. 

310. 
312. 
313. 
316. 
317. 
318. 
320. 
321. 
323. 

324. 

325. 


328. 
330. 
331. 
332. 
334. 

335. 

336. 

337. 
339. 

340. 


The  Use  of  Lumber  on  California  Farms. 

Commercial  Fertilizers. 

A  Study  on  the  Effects  of  Freezes  on 
Citrus  in  California. 

I.  Fumigation  with  Liquid  Hydrocyanic 
Acid.  II.  Physical  and  Chemical  Pro- 
perties of  Liquid  Hydrocyanic  Acid. 

I.  The  Carob  in  California.  II.  Nutritive 
Value  of  the  Carob  Bean. 

Plum  Pollination. 

Mariout  Barley. 

Pruning  Young  Deciduous  Fruit  Trees. 

The  Kaki  or  Oriental  Persimmon. 

Selections  of  Stocks  in  Citrus  Propagation. 

The  Effects  of  Alkali  on  Citrus  Trees. 

Control  of  the  Coyote  in  California. 

Commercial  Production  of  Grape  Syrup. 

Heavy  vs.  Light  Grain  Feeding  for  Dairy 
Cows. 

Storage  of  Perishable  Fruit  at  Freezing 
Temperatures. 

Rice  Irrigation  Measurements  and  Ex- 
periments in  Sacramento  Valley,  1914- 
1919. 

Prune  Growing  in  California. 

Dehydration  of  Fruits. 

Phylloxera-Resistant  Stocks. 

Walnut  Culture  in  California. 

Preliminary  Volume  Tables  for  Second- 
Growth  Redwoods. 

Cocoanut  Meal  as  a  Feed  for  Dairy  Cows 
and  Other  Livestock. 

The  Preparation  of  Nicotine  Dust  as  an 
Insecticide. 

Some  Factors  of  Dehydrater  Efficiency. 

The  Relative  Cost  of  Making  Logs  from 
Small  and  Large  Timber. 

Control  of  the  Pocket  Gopher  in  California. 


CIRCULARS 

No.  No. 

70.  Observations    on    the    Status    of    Corn  165. 

Growing  in  California. 

82.  The  Common  Ground  Squirrels  of  Cali-  166. 

fornia.  167. 

87.  Alfalfa.  169. 

110.  Green  Manuring  in  California.  170. 

111.  The  Use  of  Lime  and  Gypsum  on  Cali- 

fornia Soils.  172. 

113.  Correspondence  Courses  in  Agriculture.  173. 

115.  Grafting  Vinifera  Vineyards.  174. 

126.  Spraying  for  the  Grape  Leaf  Hopper.  175. 

127.  House  Fumigation. 

128.  Insecticide  Formulas.  176. 

129.  The  Control  of  Citrus  Insects. 

130.  Cabbage  Growing  in  California.  177. 
135.  Official  Tests  of  Dairy  Cows.  178. 
138.  The  Silo  in  California  Agriculture.  179. 
144.  Oidium  or  Powdery  Mildew  of  the  Vine. 

148.  "Lungworms."  181. 

151.  Feeding  and  Management  of  Hogs.  182. 

152.  Some  Observations  on  the  Bulk  Handling 

of  Grain  in  California.  183. 

153.  Announcement    of    the    California    State  184. 

Dairy  Cow  Competition,  1916-18.  188. 

154.  Irrigation    Practice    in    Growing    Small  189. 

Fruits  in  California.  190. 

155.  Bovine  Tuberculosis.  193. 

157.  Control  of  the  Pear  Scab.  198. 

158.  Home  and  Farm  Canning.  201. 

159.  Agriculture  in  the  Imperial  Valley.  202. 

160.  Lettuce  Growing  in  California. 

161.  Potatoes  in  California.  203. 
164.  Small  Fruit  Culture  in  California.  205. 


Fundamentals    of    Sugar    Beet    Culture 

under  California  Conditions. 
The  County  Farm  Bureau. 
Feeding  Stuffs  of  Minor  Importance. 
The  1918  Grain  Crop. 
Fertilizing  California  Soils  for  the    1918 

Crop. 
Wheat  Culture. 

The  Construction  of  the  Wood-Hoop  Silo. 
Farm  Drainage  Methods. 
Progress  Report  on  the   Marketing  and 

Distribution  of  Milk. 
Hog  Cholera  Prevention  and  the  Serum 

Treatment. 
Grain  Sorghums. 

The  Packing  of  Apples  in  California. 
Factors  of  Importance  in  Producing  Milk 

of  Low  Bacterial  Count. 
Control  of  the  California  Ground  Squirrel. 
Extending  the  Area  of  Irrigated  Wheat  in 

California  for  1918. 
Infectious  Abortion  in  Cows. 
A  Flock  of  Sheep  on  the  Farm. 
Lambing  Sheds. 
Winter  Forage  Crops. 
Agriculture  Clubs  in  California. 
A  Study  of  Farm  Labor  in  California. 
Syrup  from  Sweet  Sorghum. 
Helpful  Hints  to  Hog  Raisers. 
County  Organizations  for  Rural  Fire  Con- 
trol. 
Peat  as  a  Manure  Substitute. 
Blackleg. 


CIRCULARS — Continued 


No. 

206.  Jack  Cheese. 

208.  Summary  of  the  Annual  Reports  of  the 

Farm  Advisors  of  California. 

209.  The  Function  of  the  Farm  Bureau. 

210.  Suggestions  to  the  Settler  in  California. 
212.  Salvaging  Rain-Damaged  Prunes. 

214.  Seed   Treatment   for   the   Prevention    of 

Cereal  Smuts. 

215.  Feeding  Dairy  Cows  in  California. 

217.  Methods    for    Marketing    Vegetables    in 

California. 

218.  Ad -,•  anced  Registry  Testing  of  Dairy  Cows. 

219.  The  Present  Status  of  Alkali. 

220.  Unfermented  Fruit  Juices. 

221.  How  California  is  Helping  People  Own 

Farms  and  Rural  Homes. 

223.  The  Pear  Thrips. 

224.  Control  of  the  Brown  Apricot  Scale  and 

the   Italian   Pear   Scale   on    Deciduous 
Fruit  Trees. 


No. 

225.  Propagation  of  Vines. 

227.  Plant  Diseases  and  Pest  Control. 

228.  Vineyard  Irrigation  in  Arid  Climates. 

229.  Cordon  Pruning. 

230.  Testing  Milk,  Cream,  and  Skim  Milk  for 

Butterfat. 

231.  The  Home  Vineyard. 

232.  Harvesting     and      Handling     California 

Cherries  for  Eastern  Shipment. 

233.  Artificial  Incubation. 

234.  Winter  Injury  to  Young  Walnut  Trees 

During  1921-22. 

235.  Soil  Analysis  and  Soil  and  Plant  Inter- 

relations. 

236.  The  Common  Hawks  and  Owls  of  Cali- 

fornia   from    the    Standpoint    of    the 
Rancher. 

237.  Directions  for  the  Tanning  and  Dressing 

of  Furs. 


